BOOLEAN ALGEBRA AND LOGIC FAMILIES

Short notes

Objective questions (Answers are given below)

Boolean algebra is essential based on
(a) symbols (b) logic
(c) truth (d) numbers
The first person who used Boolean algebra for
the design of relay switching circuits was
(a) Aristotle (b) Boole
(c) Shannon (d) Ramanujam
Different variables used in Boolean algebra can
hvae values of
(a) 0 or 1 (b) low or high
(c) true or false (d) On or OFF.
According to the algebra of logic, (A + A) equals
(a) A (b) 1
(c) 0 (d) AA .
According to the absorptive Laws of Boolean
algebra , expressioin (A + AB) equals
(a) A (b) B
(c) AB (d) A
When we demorganize A B , we get
(a) AB (b) A + B
(c) A + B (d) AB .
The dual of the statement (A + 1) = 1 is
(a) A . 1 = A (b) A . 0 = 0
(c) A + A = A (d) A . A = 1.
The expression ABC can be simplified to
(a) A. B . C (b) AB + BC + CA
(c) AB + C (d) A + B + C .
While obtaining minimal sum-of-products expression,
(a) all don’t cares are ignored
(b) all don’t cares are treated as logic 1s
(c) all don’t cares are treated as logic 0s
(d) only such don’t cares that aid minimization
are treated as logic 1s.
In a saturated bipolar logic circuit, transistor
operate
(a) in deep cut-off (b) over active region
(c) in saturation
(d) just short of saturation
Saturated logic circuits have inherently
(a) short saturation delay time
(b) low switching speed
(c) higher power dissipation
(d) lower noise immunity.
Noise margin is expressed in
(a) decibel (b) watt
(c) volt (d) phon
DTL family employs
(a) resistors and transistors
(b) diode and resistor
(c) diode and transistors
(d) diodes, resistors and transistors.
The chief advantage of Schotty TTL logic family
is its least
(a) power dissipation (b) propagation delay
(c) fan-in (d) noise immunity.
The main advantage claimed for ECL family
oflogic gates is its
(a) very large fan-in
(b) use of negative power supply voltage
(c) extremely low propagation times
(d) least power dissipation.
Special feature of an I2L logic circuit is that it
(a) uses ony high-value resistors

(b) dissipates negligible power
(c) is a bipolar saturated logic
(d) is easy to fabricate
(e) uses no biasing and loading resistors.

A unique advantages feature of CMOS logic
family is its
(a) use of NMOS circuits
(b) power dissipation in nanowatt range
(c) speed
(d) dependence on frequency for power dissipation.
CMOS circuits are extensively used for onchip
computers mainly because of their extremely
(a) low power dissipation
(b) large packing density
(c) high noise immunity
(d) low cost.
The main advantage of a CMOS logic family
over the TTL family is its
(a) much reduced power
(b) increased speed of operation
(d) extremely low cost
(d) series base resistor
CMOS logic family uses only
(a) MOSFETs and resistors
(b) NMOS circuits
(c) MOSFETs (d) bipolar transistors.
Power is drawn by a CMOS circuit only when
(a) its output is high (b) its output is low
(c) it switches logic levels
(d) in static state.
The most obvious identifying feature of a TTL
gate is its
(a) large fan-out (b) high power dissipation
(c) interconnected transistors
(d) multiemetter input transistor.
In digital circuits shottky transistors are preferred over normal transistor because of their
(a) lower propagation delay
(b) higher propagation delay
(c) lower power dissipation
(d) higher power dissipation
A unique operting feature of ECL circuit is its
(a) very high speed
(b) high power dissipation
(c) series base resistor
(d) compatibility with other logic series.
The fan-in a logic gate refers to the number of
(a) input devices that can be connected
(b) input terminals (c) output terminals
(d) circuits output can drive
Which of the following statements regarding
ICs is not correct,
(a) ECL has the least propagation delay
(b) TTL has the largest fan out
(c) CMOS has the biggest noise margin
(d) TTL has the lowest power consumption.
The Boolean equation for NOR gate is
(a) AB = C (b) A + B = C
(c) A + B = C (d) A + B = C.
The Boolean equation for a NAND gate is
(a) A + B = C (b) AB = C
(c) A + B = C (d) A + B = C
The logic function of an invertor is
(a) B = A (b) B = A
(c) B = A (d) None of these
The simplified form of the Boolean expression
Y =(A.BC + D) (A.D + B.C) can be written as
(a) A.D+ B.C.D (b) AD+ B.C.D
(c) (A + D) (B.C + D) (d) A.D + BC.D

(b) 2. (c) 3. (a) 4. (b) 5. (a) 6. (c) 7. (b) 8. (d) 9. (d) 10. (c) 11. (b) 12. (c) 11.(d) 14. (b) 15. (c) 16. (e) 17. (b) 18. (b) 19. (a) 20. (c) 21. (c) 22. (d) 23. (a) 24. (a) 25.(b) 26. (d) 27. (d) 28. (d) 29. (b) 30. (a)

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